Railway traffic controlling apparatus



June 20, 1939. 1 M PE| |KAN 2,162,859

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed March 3l, 1938 -6 'V ZE4I611 p3 Plaie @Lz/peni f BY g Patented June 20, 1939 UNITED STATES 'PATENT OFFICE RAILWAY TRAFFIC CONTROLLING APPARATUS Application March 31,

6 Claims.

My invention relates to railway trailic controlling apparatus, and has for an object the provision of novel and improved apparatus for pro- Viding sensitive track circuits. A further object of my invention is the provision of means to check the integrity of the Various elements of track circuits.

I shall describe two forms of apparatus vembodying my invention, and shall then point out 10 the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a diagram illustrating certain characteristics of an electron tube. Figs. `2 and 3 are diagrammatic views of two forms of apparatus each embodying `16 my invention.

Similar reference characters refer to similar parts in each of the several views.

Referring to Fig. 1, the diagram constituting this view relates to a characteristic of an elec- 20 tron tube having aplate, a grid and a cathode. The diagram is plotted between grid voltage as abscissae and plate circuit current as ordinates, plate Voltage being constant, and the diagram illustrates the relation between the grid voltage g5 and plate current. For a given plate voltage, it

will be noted that the plate current has its lminimum value when the grid voltage has its maximum negative value, and as the negative grid Voltage decreases toward Zero voltage, the plate current increases. It is to be noted that the point of zero grid voltage is approximately on the upper end of the straight line portion of the performance curve of the tube. It is to be noted further that at certain values a vslight change in the negative grid voltage causes a relatively large change in plate current.

Referring now to Fig. 2, the reference characters I and Ia designate the track rails of a stretch of railway track which are divided by means of 0 the usual insulated rail joints 2 to form a track section D-E. Connected across the rails at one end of the section is a suitable source of current, such as track battery 3.

The reference character T designates an electron tube which, as lhere shown, comprises a heating larnent 4, a cathode 5, a grid 6 and a plate 1. 'Ihe heating element 4 is constantly heated by current from a secondary winding 8 of a transformer J, a primary Winding 9 of transformer J being connected to a suitable source of alternating current, such as a generator, not shown.

A direct current relay TR is controlled by tube T, the relay TR being interposed in a plate cir- 5| cuit for tube T, which circuit may be traced from 193s, serial No. 199,236

terminal B of a suitable source of current, such as a battery, not shown, through the winding of relay TR, primary winding I0 of a transformer J I to be referred to later, plate 1, intervening tube space to cathode 5 of tube T and terminal .'.5

C of the source of current. The plate circuit for tube T is controlledby the grid circuit for the tube. This grid circuit passes from the negative terminal of battery 3, through rail I to the negative terminal of a suitable source of current, such l as battery I2, the positive terminal of battery I2, cathode 5, tube space to grid 6, secondary winding I3 of a transformer J2, to be referred to later, and rail I a to the positive terminal-of battery 3. It is to be noted that the batteries 3 and I2 are included in the grid circuit in a manner such that the electromotive force of battery 3 opposes the electromotive force of battery I2. A resistor R is preferably connected across the grid and cathode of tube T.

A primary winding I4 of the transformer J2 is connected to a secondary winding I5 of transformer J. A secondary winding I I of transformer J I is connected with the winding of a relay TC; included in the circuit for relay TC is an asymmetric unit I6, such as is used to permit a direct current relay to be energized by an alternating current source.

A control apparatus circuit passes from terminal B through front contact I1 of relay TR and front contact I8 of relay TC to the control apparatus. As the form of the control apparatus forms no part of my present invention, it is illustrated conventionally on the drawing. The parts are so proportioned that, with the track section D-V-E unoccupied, the electromotive forces of battries 3 and I2 substantially balance and the steady voltage of grid 6 is approximately zero voltage, with the result that the direct current component of the plate circuit current is relatively large and the relay TR is energized sufciently to pick up, closing front contact I1.

The transformer J2 superimposes an alternating electromotive force on the ygrid circuitwhich causes the voltage of grid 6 to be alternately positive and negative vin step with the alternating voltage induced in the secondary winding I3 of transformer J2. This alternating grid voltage produces an alternating current component of the plate circuit current which in turn induces in the secondary winding II of transformer J I an alternating electromotive force that, when rectified by the asymmetric unit I6, eifectively energizes the relay TC. The parts are further so proportioned that under this normal condition (track section D-E unoccupied) the direct current component of the plate circuit current effectively ener-gizes relay TR and the alternating current component effectively energizes relay TC.

When a train enters the track section D-E, the Wheels and aXles of the train shunt battery 3 so that the grid 6 has a steady negative grid voltage substantially equal to the voltage of battery I2. The parts are so proportioned that the steady negative grid voltage impressed upon grid E of tube T when a train shunts the track battery 3 reduces the direct current component of the plate circuit current to such a low value that the relay TR is deenergized to a point below its release value and the relay is released, opening front contact il interposed in the controlrcircuit. It should be noted that the alternating current component of the plate circuit current may under this steady negative grid `voltage condition be insucient to eifectively energize relay TC but operation of relay TC at this time is immaterial.

Then, when the train vacates track section D-E, the shunt path around battery 3 is removed and the steady grid voltage again becomes of the order such that the direct current component of the plate current is sufficient to energize relay TR; relay TR becomes energized and closes front contact ll to complete the circuit for the control apparatus.

The relay TC acts as a tube integrity check relay. That is to say, relay TC will only become energized if the alternating voltage current supern imposed upon the steady voltage of the grid ciruit is amplified by the action of the tube T. In the event a short circuit is established across the grid and plate, or plate and cathode, and the tube can no longer act as an amplifier, the alternating current superimposed upon the grid circuit is no longer reproduced in kind on the plate circuit, so that relay TC becomes deenergized and opens front contact I 8 to open the circuits for the control apparatus.

Also, since the alternating current superimposed on the grid circuit passes through the various elements of the grid circuit, this superimposed alternating current acts as a check upon the condition of the grid circuit. That is to say, in the event of a broken rail or a broken wire in the grid circuit, the grid 6 would no longer be supplied with this alternating current, and the alternating current would no longer be amplified and reproduced in kind on the plate circuit, so that relay TC would become released and open Contact i3 to open the control apparatus circuit. Referring now to Fig. 3, the apparatus of Fig. 2 is modified so as to provide an alternating current track circuit for track section D-E, and to provide alternating current sources for the grid and plate circuits for tube T. The alternating current track circuit is established by connecting a secondary Winding ES of a track transformer J 3 across the track rails at one end of the section, a primary Winding 2Q of transformer J 3 being connected to a suitable source of alternating current, such as a generator not shown, and by connecting a primary Winding 2l of a transformer J4 across the rails at the other end of the section. Transformer Jil may be a step-up transformer, that is, a transformer in which the voltage in the secondary windingis relatively high in relation to the voltage in the primary winding.

A rectifying unit RU! is connected to a secondary Winding 22 of transformer Jathat is to say, the left-hand terminal of secondary Winding 22 offtransfcrmer J4, as viewed in Fig. 3, is connected to input terminal Z3 of rectifying unit RUI, and the right-hand terminal of secondary 22 is connected to input terminal 2d of unit RUi. A second rectifying unit RUZ` is connected to a secondary Winding 2l of transformer J so that the upper terminal of winding 2l, as viewed in Fig. 3, is connected to input terminal 28 of unit RUZ, and the lower terminal of Winding 2l is connected to the input terminal 2d of unit RUEZ.

The grid circuit for tube T may now be traced rom positive output terminal 25 of unit RUS through secondary winding i3 of transformer JE, grid l5, intervening tube space to cathode 5 of tube T, positive output terminal 3i! of unit RU'i, negative output terminal Si of unit RU?, and to negative output terminal 2% of unit RUE. It is to be noted that rectifying units RU! and RUZ are included in the grid circuit for tube T in such a manner that the electromotive force of'unit RU! is opposed by the electromotive force of unit RU?. A resistor Rl is preferably connected across grid (i and cathode 5.

A rectifying unit RU3 is connected with a secondary Winding 32 of transformer J so that the upper terminal of Winding 32, as viewed in Fig. 3, is connected to input terminal 33 of unit RUB, and the lower terminal of Winding 32 is connected to input terminal Sli of unit RU-B. The plate circuit for tube T may now be traced from positive output terminal 35 of unit RUS through inductance 3l, with capacitance 38 in multiple with a portion of the inductance 3l and capacitance 3Q in multiple with the remainder of inductance Si, the Winding of relay TR, primary ill of transformer J l, plate l, intervening tube space to cathode 5 and to the negative output terminal St of rectifying unit RU3. Y

It is to be noted that inductance 3l, which has in multiple with it capacitances 38 and 39, is included in the plate circuit for tube T so that the pulsating current resulting from the action of rectifying unit RUS may be smoothed out.

Under the normal condition of the apparatus, that is, track section D-E unoccupied, the electromotive force derived from the track circuit through transformer J fi and rectifying unit RUS opposes the electromotive force derived from rectifying unit RUZ with the result that the steady grid voltage is substantially zero and the direct current component of the plate circuit current is sufcient to energize relay TR at the desired value. The alternating voltage impressed on grid i5 by virtue of transformer J 2 is such as to produce an alternating current component of the plate circuit current such as to effectively energize relay TC to check the operating condition of tube T. It should be pointed out that the electromotive force derived from transformer J 2 is effective to impress an alternating voltage on the grid il through the individual elements of the units RU! and RUZ in their non-conducting direction. By the use of transformer J d a relatively high track circuit voltage can be obtained for balancing with the local biasing voltage derived from unit RUlZ so that the proportioning of the parts is not critical.

When a train enters the section D-E of Fig. 3 and shunts the track rails, the electromotive force of unit RUl is reduced to nearly zero and the steady grid voltage is that effected by unit RU? which is a negative Voltage. This negative grid voltage reduces the direct current component of the plate circuit current to a value where relay TR is released, opening front contact ll of the control circuit.

When the train vacates section D-E of Fig. 3, the wheels and axles of the train no longer shunt the track rails so that the electromotive force derived from unit RUI again opposes the electromotive force derived from unit RUZ with the result that the steady grid voltage is substantially zero; relay TR is energized by virtue of the direct current component of the plate current; and the apparatus is in its normal condition.

One advantage of apparatus embodying my invention is the provision of means wheieby a slight change, which in itself is not of an order sufficient to control a track re-lay, in track circuit voltage may be amplified so as to control a track relay. Hence, since a slight change in track circuit Voltage is effective to control the track relay, it can be seen that the voltage applied across the track rails need be varied by only a slight degree, and, therefore, a very sensitive track circuit is provided. A further advantage of my invention is the provision of means for checking the integrity of the elements of the grid circuit and of the electron tube.

Although I have herein shown and describe only two forms of railwaytrack circuit apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a section of railway track; an electron tube having a plate, a grid and a cathode; a first source of current connected across the rails at one end of the section, circuit means to connect said grid and cathode of said tube across the rails at the other end of the section,- a second source of current interposed in said circuit means and disposed to oppose the electromotive force of said first source, a plate circuit responsive to the equilibrium of electromotive force of said first and second sources, a rst relay responsive to said plate circuit, a third source of current impressed across said grid and cathode of said tube, and a checking relay controlled by the plate circuit responsive to electromotive force of said third sourceof current.

2. In combination, a section of railway track; an electron tube having a plate, a grid and a cathode; a rst source of electromotive force connected across the rails at one end of the section, circuit means to connect said grid and cathode of said tube vacross the rails at the other end of the section, a second source of electromotive force interposed in said circuit means and disposed to oppose the electromotive force of said first source to provide a steady biasing grid Voltage, a plate circuit responsive to the balancing of the electromotive forces of said first and second sources, a first relay controlled by the plate circuit and responsive to such biasing grid voltage, an alternating grid voltage provided by a third source of electromotive force connected across said grid and cathode of said tube, and a second relay controlled by the plate circuit and responsive to said alternating grid' voltage.

3. In combination, a stretch of railway track provided with a rst source of electromotive force connected across the' track rails thereof, an electron tube having a plate and a grid and a cathode, a circuit including said track rails for applying said first source of electromotive force across the grid and cathode of said tube whereby the conductivity of said tube is renedred responsive to traic conditions on said stretch of track, means for impressing a second source of electromotive force across the grid and cathode of said tube, a plate circuit for said tube including a source of current, control means responsive to the current flowing in said plate circuit as affected by said rst source of electromotive force, and checking means responsive to the current flowing in said plate circuit as affected by said second source of electromotive force.

4. In combination, a stretch of railway track provided with a rst source of electromotive force connected across the track rails thereof, an electron tube having a plate and a grid and a cathode, a circuit including said track rails for applying said first source of electromotive force across the grid and cathode of said tube whereby the conductivity of said tube is rendered responsive to traflic conditions on said stretch of track, means for applying a source of alternating electromotive force across the grid and cathode of said tube, a plate circuit for said tube including a source of current, control means interposed in said plate circuit responsive to the current flowing in said plate circuit as affected by said first source of electro-motive force, and checking means inductively coupled with said plate circuit and responsive to the current ow.- ing in said plate circuit as affected by said source of alternating electromotive force.

5. In combination, a stretch of railway track provided with a first source of electromotive force connected across the track rails thereof, an electron tube having a plate and a grid and a cathode, a circuit including said track rails for applying said first source of electromotive force across the grid and cathode of said tube whereby the conductivity of said tube is rendered responsive to trafc conditions o-n said stretch of track,

means for applying a source of alternating electromotive force across the `grid and cathode of said tube, a plate circuit for said-tube including a source of current, control means responsive to the direct current component of the current flowing in said plate circuit as affected by said first source of electromotive force, and checking means responsive to the alternating current component of the current owing in said plate circuit as affected by said source of alternating electromotive force.

6. In combination, a stretch of railway track provided with a rs't source of alternating electromotive force connected across the rails thereof, anV electron tube having a plate and a grid and a cathode, circuit means including said track rails for inductively coupling said first source of alternating electromotive force across the grid and cathode of said tube, a rectifier interposed in said circuit means for rectifying the current owing therein into unidirectional current, a second source of alternating electromotive force, means for applying said second source of alternating electromotive force across the grid and cathode of said tube, a plate circuit for'said tube including a source of current, control means responsive to the current flowing in said plate circuit as affected by said rst source of alternating electromotive force, and checking means responsive to the current owing in said plate circuit as affected by said second source of alternating electromotive force.

JOHN M. PELIKAN. 

